The hypothesis that food intake during the preweaning period markedly influences the number of adipocytes of the adult has had great medical impact, but has not been tested in an unequivocal fashion in regard to its validity for man and other primates. The major aim of this proposal is to rigorously test this hypothesis in the baboon. To this end, baboons have been subjected to the following 4 nursing regimens: 1) breast fed group; 2) a group formula-fed an amount of food that results in the same weight gain as breast fed, thus termed "normal" fed; 3) "overfed" group, fed 146% the amount of formula as the "normal" fed group; 4) "underfed" group, fed 64% of the amount of formula as the "normal" fed group. At 4 months of age (after weaning), the animals were changed to a prepared chow diet which simulates the cholesterol content and calories from fat of the average American diet. At present, the baboons range in age from 1-1/2 to 3-1.2 years old. The plan of this proposal is to sacrifice these baboons at 5 years of age, to excise quantitatively 10 well defined fat depots and to determine the triglyceride mass and number of adipocytes in each of these depots. In addition, the total fat mass of the baboons will be determined and the adipocyte number calculated. Besides the tests of the hypothesis just described, three kinds of ancillary information will be obtained: 1) The influence of preweaning food intake on the lean body mass of the young adult will be determined, 2) the effect of preweaning food intake on the occurence of atherosclerotic lesions in young adults will be assessed and 3) the influence of sire on the adipocyte number and mass will be assessed. This research proposal relates to our long term goal of understanding the aging process and its relation to age-related disease by providing definitive information on the possible role of early nutrition in the age-related problems of adiposity and atherosclerosis.